In recent years, various methods have been proposed for manufacturing an anti-reflection film as a film-shaped anti-reflection article by densely arranging a plurality of minute convex portions on the surface of a transparent base (transparent film) for an anti-reflection function (see Patent Documents 1 to 6). In these methods, the principle of a so-called moth eye structure is used. Specifically, the refractive index of incident light is continuously changed in the thickness direction of a substrate so as to remove a non-continuous boundary face for the refractive index, and hence an anti-reflection function is obtained.
In general, such a moth eye structure is manufactured by transferring (molding) an uneven surface shape in an arbitrary resin layer using a manufacturing mold plate such as a mold having a shape in which a minute uneven surface shape with a plurality of minute convex portions is reversed. Accordingly, as a method of manufacturing the anti-reflection film with the moth eye structure, a method may be used in which a resin layer is formed on a substrate by a curable base such as an ultraviolet curable resin, a moth eye structure is molded in the surface of the resin layer by using the above-described manufacturing mold plate, and the resin layer is cured. According to such a manufacturing method, it is possible to continuously manufacture an anti-reflection film by a simple method and with high efficiency.
Furthermore, as the mold plate of the moth eye structure, a mold (for example, see Patent Documents 1 to 3) having a concave portion formed by laser interferometry or a mold (for example, see Patent Documents 4 to 6) having a concave portion formed by an anodization method is used. Among these, since the anodization method has advantages in which a concave portion forming position may be set randomly and the concave portion may be formed with a uniform shape over a large area, the mold plate formed by the anodization method is widely used as the anti-reflection article manufacturing mold plate.
It is desirable to manufacture the anti-reflection article with high efficiency according to a roll-to-roll process by using a so-called roll plate a peripheral surface of which is provided with an uneven surface shape provided to mold the moth eye structure as a mold plate. Thus, various methods of manufacturing an anti-reflection article by using such a roll plate are proposed (see Patent Document 7).
Incidentally, there is a case in which the properties of the anti-reflection article are degraded due to the degradation of the roll plate used for the manufacturing process for a long period of time. The present inventor has carefully examined this drawback, and has found that some defects occur in certain points or areas of the roll plate because the molded minute uneven structure adheres to the resin layer provided for the molding process and is partially peeled off from the mold when the minute uneven structure is peeled off after the mold.
When the mold is degraded, there is a need to manufacture a mold having the same minute uneven structure as that of the mold without any degradation and to replace the old mold with new one. As a method of reducing the high cost spent for exchanging the mold, Patent Document 2 discloses a method in which a replicative mold (master die) manufactured by a replicating process of obtaining and reversing the minute uneven surface shape once or at least twice is used as the mold used to mold the moth eye structure instead of the original mold (mother die) having the minute uneven surface shape formed thereon on the first occasion. Since the master die of the mold may be easily manufactured again from the mother die, this method is excellent from the viewpoint of industrial productivity and cost, and hence the mold may be easily replaced when the mold is degraded.
However, even when the mold is, for example, a resinous mold plate, if such an anti-reflection article manufacturing mold plate is manufactured again for the replacement of the mold whenever slight degradation occurs, the replacement still causes a large increase in the running cost of the anti-reflection film manufacturing line in spite of the above-described method contrived by the examination. For this reason, there has been a demand for a new method for reducing the running cost of the entire manufacturing line.
[Patent Document 1] Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. 2001-517319
[Patent Document 2] Japanese Unexamined Patent Application, Publication No. 2004-205990
[Patent Document 3] Japanese Unexamined Patent Application, Publication No. 2004-287238
[Patent Document 4] Japanese Unexamined Patent Application, Publication No. 2001-272505
[Patent Document 5] Japanese Unexamined Patent Application, Publication No. 2002-286906
[Patent Document 6] Pamphlet of PCT International Publication No. WO2006/059686
[Patent Document 7] Japanese Unexamined Patent Application, Publication No. 2005-156695